ALTER TABLE DROP COLUMN

To remove a column from an existing table in Oracle, you use the ALTER TABLE DROP COLUMN command. It’s part of the ALTER TABLE command, and uses the standard “drop” word from removing something from an object.

If you specify the COLUMN keyword, you don’t need brackets for the column names.

If you don’t specify the COLUMN keyword, you must specify brackets for the column names.

You can specify more than one column to drop. Just use commas to separate the columns.

If there are columns that refer to the dropped columns using constraints, then you need to specify CASCADE CONSTRAINTS at the end of the statement. If this is not done, you will get an error. If you don’t have any columns that have these referential constraints, then you don’t need the CASCADE CONSTRAINTS clause.

Here are some examples of using the ALTER TABLE DROP COLUMN command to drop columns: